Area light direction is wrong with custom materials

The direction of area light is lighting the opposite direction it should be.

It seems that there is a difference on how the RT1.1 is setting the area light direction for custom and default materials. For custom material it is inverted, apparently because the shader code expects the direction in that way.

Instead of fixing the RT2.0 to set the direction the same way as RT1.1, this should be fixed so that both materials use the direction in same direction by changing the material shaders.